Methods and Limitations
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Methodology

We estimated the prevalence of self-reported mobility limitation among the U.S. diabetic adult population aged 18 years and older using data from the CDC's National Health Interview Survey (NHIS) of the National Center for Health Statistics (NCHS). Conducted continuously since 1957, NHIS is a health survey of the civilian, noninstitutionalized, household population of the United States. The survey provides information on the health of the United States population, including information on the prevalence and incidence of disease, the extent of disability, and the use of health care services. The survey design has been described elsewhere.1,2

Adult respondents are asked whether a health professional had ever told them they had diabetes. To exclude gestational diabetes, women are asked whether they had been told they had diabetes other than during pregnancy. Adult respondents are asked about their difficulties in doing certain activities because of a health problem. Four tasks asked in the following questions are analyzed in this report: “By yourself, and without using any special equipment, how difficult is it for you to …” “walk a quarter of a mile-about 3 city blocks” (walk a quarter mile); “walk up 10 steps without resting” (climb up 10 steps); “stand or be on your feet for about 2 hours” (stand for 2 hours); “stoop, bend, or kneel” (stoop, bend, or kneel). The responses are scaled as 0 (not at all difficult), 1 (only a little difficult), 2 (somewhat difficult), 3 (very difficult), and 4 (can’t do at all). A response with score greater than zero was identified as being limited in the task. Any mobility limitation is defined as being limited in any of the four tasks. Observations with missing value in any of the four tasks were excluded from analysis.

The prevalence estimates of mobility limitation in the diabetic population are presented by age, race/ethnicity, and sex. Three-year averages were used to improve annual estimates. The ethnic groups include people of both Hispanic and non-Hispanic origin. Estimates were age-adjusted to the 2000 U.S. Standard Population using four age groups (18–44, 45–64, 65–74, and 75 or more).
 

Limitations

Mobility limitations in the NHIS are self-reported and, thus, reflect respondents’ perception of their functioning. Further research is needed to understand the correlation between self-reported physical limitations and objective measurements of these limitations. In addition, institutionalized people were not sampled in NHIS and thus these results can only apply to noninstitutionalized population.

 

References

  1. Massey JT, Moore TF, Parsons VL, Tadros W. Design and estimation for the National Health Interview Survey, 1985–94. Hyattsville, MD: National Center for Health Statistics. Vital and Health Statistics, Series 2, No. 110, 1989.
  2. Botman SL, Moore TF, Moriarity CL, Parsons VL. Design and estimation for the National Health Interview Survey, 1995–2004. National Center for Health Statistics. Vital and Health Statistics, Series 2, No. 130, 2000.